LOW-CONCENTRATION-RATIO ULTRAFILTRATION FOR CHEDDAR CHEESE MANUFACTURE - PART 2 - EFFECT ON MATURATION

Seasonal variation in milk composition has a major effect on cheese ma nufacture, particularly during the Gate-lactation period (April and Ma y), when the cheesemilk exhibits poor syneretic properties resulting i n high-moisture cheese. However, the moisture level of cheese made fro m low-functionality milk can be controlled using cheesemilk concentrat ed by low-concentration-ratio ultrafiltration (LCR-UF). In this trial, cheddar cheese was manufactured over the late-summer, autumn and spri ng periods of a manufacturing season using LCR-UF and the effect on ch eese maturation was investigated. During the maturation period, there was a slight decrease in accumulated trichloroacetic acid (TCA)soluble nitrogen as cheesemilk protein levels increased, although there was l ittle variation in the phosphotungstic acid (PTA)-soluble nitrogen. Th e lower TCA-soluble nitrogen was most probably related to the lower MF FS, as small changes in MFFS can affect the activity of both the micro -organisms and enzymes associated with casein degradation and flavour development. Objective textural characteristics, as well as a consumer evaluation, indicated some differences throughout maturation between control cheeses and cheeses manufactured using LCR-UF milks. Control c heeses were perceived by consumers in some of the evaluations at three months as being paler in colour, less firm and having more flavour, a lthough there was no difference in overall acceptability. Al six and 1 2 months, there was little difference between the cheeses. Rheological studies also showed that cheeses manufactured using LCR-UF milks, par ticularly at 4.5% and 5.0% protein levels, had increased values in ter ms of hardness, gumminess, chewiness and elasticity. When evaluated by a professional grader, cheeses made using LCR-UF cheesemilks were gen erally graded equal to or higher than the control cheese. There was ev idence of calcium lactate crystallisation to a small extent in some ch eeses, including controls, however there was little to suggest the pro blem should be more prevalent in cheeses made with LCR-UF. The lactose in the moisture phase of the cheesemilk was relatively constant with increasing protein concentration and at 12 months L(+)- and D(-)-lacta te levels were similar in the control and LCR-UF cheeses.